This book relies on original research on Pope Gregory the Great, and on Leander, evident in Saint Leander, Archbishop of Seville, edited and translated by John R. C. Martyn (Lexington Books, New York, 2009). It starts with Gregory's letters, translated into English, to Leander, who became a very close friend. Their childhood years and very similar upbringings are followed by their years together in Constantinople, where Leander played a key role in the greatest of Gregory's works, his Commentary on Job. Their similar literary skills evident in their works are then discussed, and their theological influence, in Italy and Spain, followed by their very similar attitudes to nuns and abbesses, to heresies, schisms and monks, and to Classical Studies and music. The book ends with the overall similarities in their lives and in their deaths, both struck by gout. Gregory and Leander were two extraordinary men, who played a major part in spreading the Christian Church, both of them very much on the side of women.